Mounjaro and Tirzepatide: What's the Difference Between Them?

Are Mounjaro and tirzepatide literally the same medicine?

Yes. Tirzepatide is the International Nonproprietary Name (INN), the official scientific name used by regulators, clinicians and researchers worldwide. Mounjaro is the proprietary name Eli Lilly registered for the product. The relationship is identical to paracetamol and Panadol, or ibuprofen and Nurofen: one active ingredient, one set of clinical properties, and multiple ways of referring to it depending on context.

When the NICE technology appraisal TA1026 recommended tirzepatide for weight management in December 2024, it evaluated the same medicine you receive in a Mounjaro KwikPen. The trial evidence, the side-effect profile, the licensed dosing schedule, all of it belongs to both names simultaneously.

If a search or a conversation has led you to wonder whether Mounjaro and tirzepatide are somehow different products at different prices or strengths, the short answer is no. The longer answer is that understanding why both names exist helps you make sense of what you read. You can explore how tirzepatide compares across different contexts if you want the full breakdown of how the name shifts depending on the source.

What makes tirzepatide/Mounjaro distinct from other weight-loss medicines?

Tirzepatide is the only weight-loss medicine currently licensed in the UK that acts on two gut-hormone receptors simultaneously. It is a dual GIP and GLP-1 receptor agonist, which means it activates pathways involving both glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1). Semaglutide (the active ingredient in Wegovy) works on the GLP-1 receptor alone. Understanding that distinction is one reason the difference between GLP-1 and tirzepatide's dual mechanism gets its own explanation.

In clinical trials, tirzepatide produced average weight reductions of around 20–21% at the 15mg dose over 72 weeks (SURMOUNT-1, published in the New England Journal of Medicine). The SURMOUNT-5 head-to-head trial in 2025 found tirzepatide produced greater average weight loss than semaglutide 2.4mg over the same period. Those numbers belong to the medicine itself, the brand name on the pen does not change them.

Liraglutide works differently again; if you are curious about the wider landscape, there is a separate page on the difference between liraglutide and tirzepatide that covers the mechanism and evidence in detail.

Does the name affect cost, availability or prescription?

No. The price of treatment reflects the medicine itself, not which name appears on the packaging, and in practice, only one branded product exists in the UK: Mounjaro. There is no generic tirzepatide available here yet, so the name difference is currently academic from a buying perspective.

Cost does vary by dose and provider. Since Eli Lilly revised Mounjaro's UK list price in September 2025, reported private prices have ranged from roughly £149 to £375 per month depending on strength and the service supplying it. Our Mounjaro cost breakdown explains what those figures typically do and do not include. Whatever the price, legitimate supply requires a valid UK prescription, the medicine cannot legally be dispensed without one. If you are comparing providers, verifying any online pharmacy on the GPhC register takes under a minute and is the single most useful check you can do before handing over any details.

On the NHS, tirzepatide is being rolled out in phases under NICE TA1026. Private access through a registered pharmacy is an alternative for people who do not yet meet NHS criteria or prefer not to wait. Our full Mounjaro guide covers eligibility, the licensed dosing schedule and what private treatment involves.

How do Mounjaro/tirzepatide and semaglutide compare at a glance?

The table below sets out the key factual differences between Mounjaro (tirzepatide) and Wegovy (semaglutide), the two injectable medicines currently licensed for weight management in the UK. It is not a recommendation, which one suits your health picture is the sort of question our prescribers work through with you at consultation.

Note: Ozempic is also semaglutide, but it is licensed for type 2 diabetes, not weight management. It should not be conflated with Wegovy, and it is not something a UK prescriber can lawfully supply for weight loss. The weight-loss treatment overview explains which medicines are licensed for which purposes.

For readers curious about newer molecules in development, there is also a look at how Mounjaro differs from retatrutide, a triple-agonist candidate not yet licensed in the UK.

Which of the licensed options suits you is a clinical decision. Check your eligibility with our prescribers and they will assess both your health history and your goals before recommending a starting point.